Hydrodynamics in falling liquid films on surfaces with complex geometry

•Liquid nitrogen spreading over the corrugated plates was studied experimentally.•The effect of irrigation density on the zones of nitrogen film spreading is shown.•A effect of the flow rate on intensity of flow across the channel crests is revealed.•Microtexture has a significant effect on the liquid film spreading.•The character of liquid spreading depends considerably on angle of rib inclination. These studies include investigation of the character of liquid spreading over the surfaces with complex geometry, the effect of microstructure, corrugation angle, and perforation on the wave film flow. The paper present the results of experimental studies on dynamics of the film flow of cryogenic liquid over the complex surfaces: vertical plane and ribbed aluminum plates with/without wave microtexture. Experimental results were obtained at the flow of liquid nitrogen. According to results of experiments on the ribbed structured perforated aluminum surfaces with the use of highly wetting low-viscous liquids, the film flow character depends significantly on the irrigation rate. The direction and parameters of microstructure, the angle of inclination of the main fins, position and diameter of holes effect significantly the zones of liquid spreading and its distribution over the surface of the ribbed structured plates, especially, within the range of low liquid flow rates. According to high-speed video recording, in case of horizontal microstructure the wave dynamics influences considerably liquid redistribution in transverse direction. This is caused by the fact that liquid flows intensively at propagation of secondary waves along the channels of horizontal microstructure. Experimental results on dependence of the relative portion of liquid, held in a single irrigated channel of the corrugated plates with different thicknesses, on the irrigation degree are presented.